Catheter placement device

ABSTRACT

A catheter placement device including a Teflon catheter with an imperforate, generally hemispherical tip and two laterally opening ports adjacent the tip, the catheter being telescoped onto a cannula which bears against an annular internal shoulder behind the tip and communicates with the ports. The device is gripped by handles attached either directly to a hub on the cannula or to an adapter releasably connected to the hub, and is inserted through a shallow incision made with a disposable introducer formed in one piece with a troughlike pointed shank and an integral grip which centers the thrust of insertion on the shank. A capillary tube and a syringe are included as alternative sensing devices for communicating through the cannula with the ports to determine when a change in condition occurs during placement.

United States Patent 3/1963 Hunter 10/1967 Foderick ABSTRACT: A catheterplacement device including a Teflon catheter with an imperforate,generally hemispherical tip and two laterally opening ports adjacent thetip, the catheter being telescoped onto a cannula which bears against anannular internal shoulder behind the tip and communicates with theports. The device is gripped by handles attached either directly to ahub on the cannula or to an adapter releasably connected to the hub, andis inserted through a shallow incision made with a disposable introducerformed in one piece with a troughlike pointed shank and an integral gripwhich centers the thrust of insertion on the shank. A capillary tube anda syringe are included as alternative sensing devices for communicatingthrough the cannula with the ports to determine when a change incondition occurs during placement.

PATENTED UEC28 ran SHEET l U? 3 IN VEN TOR. M51. v m1 1. //A/A //vCATHETER PLACEMENT DEVICE BACKGROUND OF THE INVENTION This inventionrelates generally to catheters and, more particularly, to the placementof catheters in body cavities, passageways and potential spaces for thepassage of fluids through the catheter, either the withdrawal ordrainage of fluid from the body or the administration of fluid to thebody.

I-Ieretofore, the placement of catheters typically has been accomplishedwith the assistance of a sharply pointed needle for piercing the bodytissue. For some procedures, the needle itself serves as the catheterthrough which fluid is passed, while in other instances, a small-boreinternal catheter has been threaded through the bore of a needle intothe body, or a larger-bore catheter has been externally positioned on aneedle for introduction as an incident to the insertion of the needle.In the latter type of placement units, the needle point protrudes fromthe tapered leading end of the catheter to pierce the body tissue inadvance of the catheter, thereby leading the catheter through the tissueto the selected body cavity or potential space.

Where a sharply pointed needle leads the catheter through the bodytissue into, or close to, the ultimate position of the inner end or tipof the catheter, there is a distinct danger of inadvertent puncturing ofdelicate tissue and organs disposed in the path of the needle but beyondthe intended area of penetration. For example, for epidural anethesia, acatheter is inserted into the spinal structure through the interspinousligaments and the bordering ligamentum and into the epidural space,wherein the point of the needle is very close to the dura. If there is avery slight misjudgment, a dural puncture can occur, with seriousresults for the patient. There are many similar situations, well knownto those skilled in the art, in which the use of sharp needles in theplacement of conventional catheters involves a danger of inadvertent andharmful punctures.

SUMMARY OF THE INVENTION The present invention resides in a relativelysimple and inexpensive catheter placement device which eliminates theneed for a needle for leading the catheter into its final position,which also may be forced with relative ease and control through bodytissue, and which provides a ready indication of the arrival of thecatheter at the desired position before there has been excessivepenetration. More specifically, the preferred embodiment of theinvention includes a disposable catheter that is composed oflow-friction plastic material and is telescoped over a longitudinallystiff cannula, the catheter being formed with an imperforate tip thatcovers the leading end of the cannula and is shaped for blunt dissectionof tissue. The interior of the cannula communicates through the tip withat least one port that opens laterally out of the catheter adjacent thetip, and the leading end of the cannula bears against an end wall of thecatheter behind the tip. For application of the force required to drivethe catheter through the tissue to be penetrated, the trailing end ofthe cannula has a hub with means enabling the user to maintain a firmgrip thereon.

To provide a prompt and reliable indication of the entry of the tip intoa body cavity, the hub of the cannula also has a seat for attachment ofa sensing device, e.g., a capillary tube or a syringe, operable toindicate a change in fluid condition at the tip of the catheter, andthus to signal the entry of the ported portion of the catheter into abody cavity. The grip and sensing device may be mounted directly on thecannula hub, or may be mounted on a special adapter seated against thehub.

To facilitate initial insertion of the catheter through the skin and toaid in directing it toward the body cavity, the invention includes anovel, disposable introducer for making an incision in the skin andguiding the placement device through the tougher outer tissue layersinto the underlying softer tissue. The introducer is of simpleconstruction that may be mass produced at relatively low cost with asharp and effective point, and has a novel grip for more effectiveapplication of the thrust of insertion so as to eliminate torque tendingto bend the introducer during use. Accordingly, the introducer is aneasily fabricated and inexpensive tool which is disposable after use,and yet is highly effective for its intended purpose, as compared withprior instruments designed for the same general purpose.

Other objects and advantages of the invention will become apparent fromthe following detailed description, taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an enlarged side elevationalview of a catheter placement device embodying the novel features of thepresent invention, with part of the central portion broken away forcompactness and part shown in cross section for clarity;

FIG. 2 is an enlarged fragmentary cross-sectional view of the tip andthe adjacent portion of the device, taken substantially along the line2-2 of FIG. 1;

FIG. 3 is a view similar to FIG. 2 with the cannula removed;

FIG. 4 is an enlarged cross section taken along the line 4-4 of FIG. 1;

FIG. 5 is a fragmentary perspective view illustrating the insertion ofthe introducer through the skin;

FIG. 6 is a view similar to FIG. 5 with the catheter placement devicepositioned for insertion along the introducer;

FIG. 7 is a fragmentary sectional view taken in a plane extendinglongitudinally of the device and showing the device as it is insertedalong the introducer into a body cavity;

FIG. 8 is an exploded view similar to FIG. 7 after the introducer andthe cannula have been removed from the patient and the catheter,respectively;

FIG. 9 is an enlarged fragmentary view, partly in cross section andpartly in side elevation, showing a modified form of the invention withhandles and a capillary tube incorporated in the hub of the cannula;

FIG. 10 is a view similar to FIG. 9 showing a second modified form witha detachable connector releasably coupled to the hub of the cannula andto the barrel of a syringe for communicating through the connector andthe cannula with the tip of the catheter;

FIG. 11 is a view similar to FIG. 10 in which a capillary tube has beenapplied to a detachable connector;

FIG. 12 is an enlarged perspective view of the introducer;

FIG. 13 is an end view thereof;

FIG. 14 is a side elevation thereof including a fragmentary view of agrinding wheel for sharpening the point;

FIG. 15 is a plan view;

FIG. 16 is a plan view of a substantially fiat blank prior to bendingand sharpening of the blank to form the introducer; and

FIG. 17 is an enlarged cross-sectional view taken substantially alongthe line l7l7 of FIG. I6.

DETAILED DESCRIPTION As shown in the drawings for purposes ofillustration, the invention is embodied in a device, indicated generallyby the number I0, for use in inserting an elongated, tubular catheter 11through body tissue 12 (FIGS. 5-7) until the inner end portion or tip 13of the catheter is disposed within a body cavity 12,, (FIG. 7) for theeventual passage of fluid through the catheter 11 into or out of thecavity, as determined by the particular medical treatment being providedfor the patient. Examples of the use of catheters are epiduralanesthesia, in which the anesthetic is passed through the catheter intothe epidural space, paracentesis of pericardial effusion, in which fluidaround the heart is withdrawn through a needle serving as a catheter;and cerebral ventricular drainage, in which liquid is drained through acatheter placed in a ventricle of the brain. There are, of course, manyother well-known uses of catheters, and including drainage of thebladder, the chest, the abdominal cavity, and subcutaneous wounds.

As previously mentioned, the usual practice has been to use a sharplypointed needle to pierce or cut through the body tissue preparatory toinsertion of the somewhat flexible catheter through the tissue, whetherthe catheter is carried on the outside of the needle to be left in placeafter the needle is withdrawn, or is small enough to be threaded throughthe needle into place prior to withdrawal of the needle over thecatheter. In some instances, a pointed, hollow needle is used not onlyto pierce the tissue but also to draw fluid from the body cavity. Wherethe catheter is externally disposed, it is desirable to use a catheterthat is either composed of or coated with a low-friction material liketetrafluoroethylene, obtained commercially under the trademark Teflon ofE. I. duPont de Nemours Co., Inc.

In any event, safe placement of a catheter is a body cavity in aconventional manner with a pointed needle that cuts through the tissue,requires very careful handling of the needle to avoid penetration to anexcessive depth, beyond the desired end point for the catheter. Thesharp point of such a needle passes through the body tissue so quicklyand smoothly as to give virtually no indication of the type of tissuebeing penetrated, and thus can pass through the wall of a cavity andpuncture delicate tissues beyond the wall before the user realizes thepoint of the needle has entered the cavity.

In accordance with a primary aspect of the present invention, thecatheter 11 is formed with an imperforate tip 13 shaped for bluntdissection of tissue, and is telescoped slidably onto a longitudinallystiff cannula 14 which has a leading end 15 for pressing against aninside abutment surface 17 behind, and closely adjacent, the cathetertip 13, to drive the latter through the body tissue. At least one port18 opens laterally out of the catheter adjacent the tip and communicatesreliably with the interior 19 of the cannula when the latter is in thecatheter. A hub 20 is provided on the outer or trailing end of thecannula with means thereon for applying the inserting force to thecannula, and thus to the tip of the catheter, and also for attachment ofan appropriate sensing device or indicator communicating through thecannula with the port or ports adjacent the tip of the catheter.

With this arrangement, the resiliently flexible catheter 11 is driventhrough the body tissue by the force applied through the cannula 14 tothe abutment surface 17 immediately be hind the tip 13 so that thecatheter sheaths the cannula, and the blunt tip of the catheter actuallyleads the cannula through the tissue and into the body cavity. Becausethe tip is blunt, there is sufficient resistance to movement to providea perceptible variation as the tip moves into a cavity, giving the usera feel" for the progress of the tip, and the blunt catheter penetratesthe tissue atraumatically, without the cutting action that ischaracteristic of a sharpened needle. In addition, no stylet is requiredto close the port or ports 18 in the catheter, and the interior of thecatheter thus remains constantly open to the port or ports for fluidpassage through the catheter to the sensing device.

In the present instance, the cannula 14 is simply a flat or blunt ended,hollow needle (see FIG. 8) having a hub 20 of basically conventionalconstruction at its outer or trailing end, the lower end as viewed inFIG. 1 and the right end in FIG. 8. The interior of the needle forms aninternal passage 19 extending from the leading end completely throughthe hub. When the placement device 10 is fully assembled, the catheter11 is telescoped onto the cannula and covers the latter from the tip tothe hub, preferably having a hub 21 on its trailing end in abutment withthe leading side 22 of the cannula hub 20.

It will be seen in FIGS. 1-4 that the catheter 1 l is formed by arelatively thin-walled tube, preferably of circular cross section,defining an internal passage 23 which extends from the abutment surface17, adjacent the upper end of the catheter in FIGS. 1-3, through thecatheter to the hub 21 thereon. Through the hub, the passage 23communicates with a seat 24 in the side of the catheter hub abuttingagainst the cannula hub 20, the seat being formed in the trailing sideof the catheter hub in relation to the direction of insertion. This seatpreferably is tapered to receive a conventional tapered fitting (notshown) for connecting an instrument or conduit to the catheter after itis placed and the cannula 14 has been removed.

Catheters are made in different' sizes, depending upon the requirementsof the particular treatment and ranging, for example from l/l6 of aninch outside diameter, or smaller, to /4 of an inch or larger. For ageneral appreciation of the illustrative embodiment, the outsidediameter may be considered as being on the order of 1/16 of an inch,thus being shown approximately full size in FIGS. 6-8. The cannula 14has an outside diameter selected to fit within the catheter with a snug,sliding fit.

As shown in FIGS. 2 and 3, the tip 13 is disposed across and closes theleading or upper end of the internal passage 23 of the catheter, has animperforate, outer leading side that is shaped for the blunt dissectionof tissue, and has an inner trailing side extending transversely acrossthe leading end of the passage 23 and forming the abutment surface 17for engagement with the transverse end surface 15 of the cannula.Preferably, the leading side of the tip is generally hemispherical, andthe transverse surfaces 15 and 17 are generally perpendicular to thelongitudinal axis of the catheter.

As shown most clearly in FIG. 1, two laterally opening ports 18 hereinare formed on opposite side of the catheter 11, immediately behind thetip 13, at the opposite ends of a crosspassage 25 in the tip, and athird port or passage 27 (FIGS. 2 and 3) extends through the centralportion of the abutment surface 17 into the center of the cross-passageto establish communication between both ports 18 and the internalpassage 19 in the cannula 14 when the latter is in place in thecatheter. The connecting port 27 has approximately the same diameter asthe inside diameter of the cannula, and is coaxially centered withrespect to the cannula and the catheter.

Thus, the abutment surface 17 is any annular internal shouldersurrounding the connecting port 27 and having approximately the sameradial width as the radial wall thickness of the cannula. It will benoted, however, that the end surface area of the cannula has beenutilized advantageously for the application of driving force through theshoulder 17 to the tip 13, and that the cannula and the connecting portare maintained positively in full communication with each other withoutregard to any changes in the relative angular positions of the parts.

Although the cross-passage 25 may be made concentric with the curvatureof the leading side of the catheter tip 13, the cross-passage of thepreferred form of the catheter is offset slightly toward the leadingside relative to its center of curvature, as is most readily seen inFIGS. 2 and 3. This reduces the amount by which the tip projects beyondthe end 15 of the cannula and correspondingly reduces any tendency thetip may have to bend over during penetration. In addition, the width ofthe tip longitudinally of the cross-passage 25 is increased slightly, asshown in FIG. 1, to thicken the tip to an almost rectangular crosssection with rounded corners. This strengths the tip and assists inkeeping the ports 18 generally in longitudinal planes nearly parallel tothe longitudinal axis of the catheter 11.

For ease of fabrication, the body of the catheter may be a shrinkableTeflon tube that is shrunk around a mandrel, and the tip 13 may bemeltable Teflon that is fused to the end of the tube and shaped betweenthe mandrel and a suitable die (not shown). These and other proceduresare within the skill of the art.

It will be seen in FIG. 1 that the trailing end portion of the catheter11 is telescoped over a tubular flange 28 of the catheter hub 21, and isanchored in an annular recess 29 of the hub. This is merely anillustrative manner of attachment of the catheter to its hub, and itwill be evident that various other mountings may be used. The catheterhub 21 simply abuts against the cannula hub 20, and does not interlocktherewith. When a nose 30 is formed on the cannula hub as shown in FIGS.and 11, this nose may fit loosely into the tapered seat 24 of thecatheter hub, but should not be locked therein.

The means for gripping the placement device 10 and applying theinserting force through the cannula 14 to the tip 13 of the catheter l1herein comprise two winglike handles 31 projecting in oppositedirections from the cannula hub 20 and rigidly secured thereto. Thesehandles may be grasped between the thumbs and forefingers of two handsduring placement of the catheter, and provide for convenient applicationof the force required to insert the catheter. As shown herein, thehandles are the opposite end portions of a single, elongated plate ofmetal or suitably rigid plastic material that is secured to the leadingend of the cannula hub.

To facilitate the proper placement of the catheter 11 in a patient, theinvention contemplates the use of a novel disposable introducer 32 (SeeFIGS. 5-7) for making an initial incision through the skin and otherouter tissue layers, and guiding the catheter through these layers intothe softer inner layers of flesh. In general, the introducer comprisesan elongated troughlike shank 33 terminating at one end in a point 34for making the incision and having a grip 35 on the opposite end portionwith which the introducer is held as the point is pressed through theskin and into the position shown in FIGS. 5-7.

With the introducer 32 thus inserted, the leading end portion of thecatheter placement device 10 is placed in the upwardly opening trough orgroove defined by the shank 33, and is slid along the shank through theincision and into the patient. If desired, a light downward movement ofthe introducer may be used to open the incision slightly to admit thecatheter.

Initially, the force required to move the placement device 10 will beslight, because of the preparatory incision made with the introducerwhich, it will be seen, is inserted a distance considerably less thanthe full depth to which the catheter is to be driven. After the cathetertip 13 passes the point 34 of the introducer, the resistance topenetration increases substantially since the tip then is forced bluntlythrough the imperforate tissue.

Although the resulting resistance to penetration is perceptible, it isnot so high as to make the placement difiicult, and the use of Teflon orthe like reduces the frictional drag on the catheter to a negligibleamount. Accordingly, relatively firm insertion pressure is all that isrequired for the blunt dissection of underlying tissue, and thevariations in resistance in going through different types oftissueincluding muscle, fascia, ligaments and other connective tissue,and the walls of organs such as the urinary bladder-are not significant.The tip of the catheter is shown in FIG. 7 as being disposed just insidethe wall 37 of the body cavity 12a.

After serving its purpose of making the initial incision and directingthe catheter 11 into the patient the introducer 32 is removed asindicated in FIG. 8. When the tip 13 of the catheter 11 has beenadvanced to its intended final position, the cannula 14 also iswithdrawn as shown in FIG. 8, leaving the catheter ready for connectionto a syringe or other instrument for the intended treatment.

The modified placement devices 10a, 10b and 10c partially shown in FIGS.9-11 illustrate various ways in which sensing devices may beincorporated in, or connected to, the cannula of the placement device toprovide a ready indication of a change in condition at the tip 13 of thecatheter, which is not shown in these views. In the form shown in FIG.9, a transparent capillary tube 38 is secured to the hub 39 of thecannula 14a with the passage 40 in the capillary tube in communicationwith the interior 19a of the cannula and, therefore, arranged forcommunication with the ports 18 adjacent the tip of the catheter 11,when the latter is in place on the cannula. Handles 31 are attached tothe hub 39, just as in the first embodiment.

Accordingly, a drop 41 of liquid placed in the capillary tube 38 willremain substantially stationary as the catheter passes through tissue,but will move in response to a pressure differential within the tube toindicate exposure of the ports 18 either to an increased pressure or toa reduced pressure. For example, a reduced pressure would occur in theepidural space as a result of deflection or tenting of the dura by theblunt tip 13, and this would cause the drop 41 to move inwardly towardthe tip of the catheter. The opposite result, an outward movement, willbe obtained as the catheter tip enters as cavity filled with fluid,either liquid or gas, under positive pressure.

It will be seen in FIG. 9 that the handles 31 are attached directly tothe hub 39 of the cannula 14a, as in the first embodiment. The cannula14b in the third form 10b, shown in FIG. 10, has a modified hub 42without any handle, but combined with an adapter 43 forming a releasableextension of the hub and having a tapered fitting 44 as its leading endfor seating releasably in a tapered socket 45 in the hub 42. Anothertapered socket 47 is formed in the trailing end of the adapter forreceiving the tapered end 48 of a syringe, only the barrel 49 of whichis shown in FIG. 10. A passage 50 in the adapter connects the socket 47to the socket 45 to establish communication between the syringe barrel49 and the bore 51 of the cannula 14b.

In this instance, handles 52 are securely attached to the adapter 43 asthe opposite end portions of an elongated plate through which the bodyof the adapter extends. Accordingly, the handles are detachable from thecannula 14 with the adapter for possible reuse if desired.

In FIG. 11, the same concept has been applied to the placement device toincorporate handles 53 and a capillary tube 54 in an adapter 55 similarto the adapter 43 of FIG. 10. In this case, the capillary tube has atapered end 57 that is seated, either permanently or detachably, in atapered socket 58 in the adapter, and the adapter has a tapered fitting59 that is releasably engaged in a tapered seat 60 in the hub 61 of thecannula 14c. Again, this arrangement permits removal of the adapter,including the handles 53 and the sensing device 54, from the cannulaafter the latter has served its purpose.

In addition to the frictional coupling accomplished by the tapered partsin the various embodiments, conventional, positive interlocks may beprovided on the parts for selective use in the usual manner. Inaddition, other well-known features may be incorporated, as desired, forspecial purposes, For example, specially shaped sockets may be providedin the hubs or connectors for connections to special-purpose instrumentsor fittings, or a so-called Foley catheter-type balloon and inflationtube may be incorporated along the length of the catheter in awell-known manner to aid in retaining the catheter in a cavity.Moreover, the leading end portion of the catheter may be trained orprestressed into a laterally bent shape which it assumes as soon as thecannula is withdrawn, again in a manner that is known. While thecatheter has been described as having one or two holes adjacent the tip,it will be apparent that additional holes (not sown) may be spaced alongthe catheter from the tip to be opened as the cannula is withdrawn,thereby to reduce the change of plugging in use and to increase the flowarea where it is desirable to do so. These and other modifications willsuggest themselves readily to those skilled in the art as being withinthe spirit and scope of the invention.

The novel introducer 32 is shown most clearly in FIGS. 12-17, wherein itwill be seen that the shank 33 is in the form of an elongated channel,preferably semicircular in transverse cross section, and that the grip35 is formed by two finger pieces including flaps 62 which extend bothabove and below the longitudinal axis of the shank, on opposite sidethereof, and have two opposed, laterally facing holes or recesses 63 forthe gripping thumb and finger of the user. These recesses are centeredon the longitudinal axis of the shank 33, and thus align the thrust ofthe users fingers with the shank to facilitate skin penetration by, andproper direction of, the shank, without significant danger of bending asa result of development of torque during insertion.

Each gripping flap 62 preferably is integrally joined to an upperlongitudinal edge 64 of the shank 33, adjacent the end thereof remotefrom the point 34, by an inner leg 65 extending upwardly from the shankand connected by an outwardly and reversely curving bend 67 to the flap62, which extends downwardly from the bend to a level well beyond theshank. The inner legs 65 preferably flare or diverge upwardly tofacilitate the placing of the catheter 11 into the groove of the shank,and the flaps preferably have slightly concave outer sides formed withsomewhat elongated finger recess 63 which are centered vertically on theshank to receive the tips of the thumb and finger of the user, as shownin FIG. 5. This assures the alignment of the thrust with the shank andthe point.

This configuration makes it possible to form the introducer 32inexpensively from a single sheet metal stamping 68 shown in FIG. 16,beginning as a T-shaped blank with a relatively narrow strip 69 forforming the shank, joined at a right angle to the center of a widerstrip 70 for the finger pieces. The finger recesses 63 may bedepressions that are stamped into theopposite end portions of the widerstrip 70 as an incident to the initial stamping operation. As a firstshaping operation, the blank may be curved, longitudinally of the narrowstrip 69, to form the trough of the shank 33, leaving the opposite endportions of the wide strip 70 in the planes-indicated at 71 in FIG. 13.Then the reverse bends 67 are formed and the concavity is applied to theflaps 62 to complete the introducer except for its point 34.

As shown in FIGS. 12, 14 and 15, the point 34 is defined substantiallyon the longitudinal centerline of the shank 33 by two arcuate, upwardlyfacing edges 72 curving concavely downwardly and converging to thepoint. The edges 72 are substantially arcs of a cylinder that is tangentto the bottom surface of the trough or channel defined by the shank.

Conventional needle-pointing techniques are not practically applicableon a mass production basis to a shank that is open sided and, thus,effectively fiat on one side. Moreover, conventional flat" grinding ofthe end of a semicylindrical shank on an angle with the longitudinalaxis of the shank will produce a generally elliptical cutting edgerather than a point, requiring additional shaping operations to reducethe edge to a point. As shown in FIG. 14, a grinding wheel 73 rotatingabout an axis 74 and having a rounded edge 75 is passed transverselyacross the end of the shank 33 while the latter is held generallyparallel to the axis 74 of the wheel, and with the centerline of theshank (the bottom of the trough) generally tangent to the arc of therounded wheel edge 75. Of course, a large number of introducers can beclamped in side-by-side relation to grind points on all the shanks in asingle pass. Thus, the novel introducer may be mass produced at lowenough cost to be disposable, and yet has a sharp, effective andnoncoring point.

It will be evident that the relationship of the radius of curva ture ofthe rounded edge 75 will determine the sharpness of the point, the easeof penetration, and the length of the point. In addition, the pointconfiguration has the advantage of tending to lift the penetrated wallof a vessel while making a fine, slitlike incision. Although theone-piece construction of the introducer, including the integral grip,is preferred for econo my of manufacture, it will be apparent to thoseskilled in the art that the grip 35 might be fabricated separately andattached to the shank 33.

From the foregoing, it should be evident that the present inventionprovides a catheter placement device 10, and cooperating introducer 32,for safe and convenient placement of a catheter 11 in a body cavity 12awithout need for a sharp needle of the type that has been used to leadthe catheter through the body tissue, with risk of inadvertent punctureof delicate tissue and organs of the body. Instead, the novel anddisposable introducer 32 is used simply to open a relatively shallow andfine incision through the tougher outer layers of tissue, and theblunt-end catheter 11 is placed in the body through the incision,leading the stiffer cannula through the tissue andpenetrating beyond thedepth of the incision by blunt dissection of tissue.

It has been seen that this is made possible by using a lowfrictionresiliently flexible material for the catheter, forming a generallyhemispherical, imperforate tip on the catheter, and applying theinserting force immediately behind the tip with a longitudinally stiff,blunt-ended cannula that not only forces the catheter through the tissueinto the desired location, but also communicates constantly with atleast one laterally opening port near the tip of the catheter. Moreover,the secondary features of the several modified forms add flexibility tothe placement device with regard to the manner of attachment of thehandle and the different representative sensing devices.

I claim as my invention:

1. A catheter placement device having, in combination:

an elongated resiliently flexible plastic catheter having an imperforatetip at one end shaped for blunt dissection of tissue, a central passageextending through said catheter from the opposite end thereof to saidtip, said passage terminating adjacent said tip in a transverse endwall, and at least one laterally opening port adjacent said tipcommunicating with said passage;

an elongated cannula disposed in said catheter in sliding,

telescoped relation therewith and having a transverse end surfaceengaging said end wall, the other end portion of said cannula projectingthrough said opposite end of the catheter;

means on said other cannula end forming a grip for said placement devicewhereby said imperforate tip is pressed through tissue by a forceapplied through the cannula against said transverse end wall; and

said cannula having a longitudinal passage opening through thetransverse end surface thereof toward said end wall, and said port insaid catheter being connected to said cannula passage by means includinga connecting passage opening through the central portion of said endwall.

2. A catheter placement device having, in combination:

an elongated catheter having an imperforate rounded tip at one end, alongitudinal passage of preselected diameter extending through saidcatheter from the end thereof opposite said tip and terminating in atransverse end wall adjacent said tip, and a connecting passageextending from said end wall into said tip, and opening laterallytherefrom to form at least one port communicating through saidconnecting passage with said longitudinal passage;

an elongated cannula having an outside diameter approximately equal tosaid inside diameter, a longitudinal internal passage, and opposite endsthrough which the internal passage opens, said cannula being disposedwithin said catheter with a sliding fit with one of its ends abuttingagainst said wall and with said internal passage communicating with saidport through said connecting passage; and

means on the other end of said cannula forming a strip for saidplacement device whereby said tip is pressed through tissue by a forceapplied through said cannula and said end wall while said port remainsin communication with said cannula passage.

3. A catheter placement device having, in combination:

an elongated resiliently flexible plastic catheter having an imperforatetip at one end shaped for blunt dissection of tissue, a central passageextending through said catheter from the opposite end thereof to saidtip, said passage terminating adjacent said tip in a transverse endwall;

an elongated cannula disposed in said catheter in sliding, telescopedrelation therewith and having a traverse end surface engaging said endwall, the other end portion of said cannula projecting through saidopposite end of the catheter;

means on said other cannula end forming a grip for said placement devicewhereby said imperforate tip is pressed through tissue by a fore appliedthrough the cannula against said transverse end wall; and

which said tip is generally hemispherical in shape and saidcross-passage is offset from the center of curvature toward said tip,said tip being thickened longitudinally of said crosspassage to a nearlyrectangular shape to dispose said laterally opening ports in planesextending substantially longitudinally of said catheter.

1. A catheter placement device having, in combination: an elongatedresiliently flexible plastic catheter having an imperforate tip at oneend shaped for blunt dissection of tissue, a central passage extendingthrough said catheter from the opposite end thereof to said tip, saidpassage terminating adjacent said tip in a transverse end wall, and atleast one laterally opening port adjacent said tip communicating withsaid passage; an elongated cannula disposed in said catheter in sliding,telescoped relation therewith and haviNg a transverse end surfaceengaging said end wall, the other end portion of said cannula projectingthrough said opposite end of the catheter; means on said other cannulaend forming a grip for said placement device whereby said imperforatetip is pressed through tissue by a force applied through the cannulaagainst said transverse end wall; and said cannula having a longitudinalpassage opening through the transverse end surface thereof toward saidend wall, and said port in said catheter being connected to said cannulapassage by means including a connecting passage opening through thecentral portion of said end wall.
 2. A catheter placement device having,in combination: an elongated catheter having an imperforate rounded tipat one end, a longitudinal passage of preselected diameter extendingthrough said catheter from the end thereof opposite said tip andterminating in a transverse end wall adjacent said tip, and a connectingpassage extending from said end wall into said tip and opening laterallytherefrom to form at least one port communicating through saidconnecting passage with said longitudinal passage; an elongated cannulahaving an outside diameter approximately equal to said inside diameter,a longitudinal internal passage, and opposite ends through which theinternal passage opens, said cannula being disposed within said catheterwith a sliding fit with one of its ends abutting against said wall andwith said internal passage communicating with said port through saidconnecting passage; and means on the other end of said cannula forming agrip for said placement device whereby said tip is pressed throughtissue by a force applied through said cannula and said end wall whilesaid port remains in communication with said cannula passage.
 3. Acatheter placement device having, in combination: an elongatedresiliently flexible plastic catheter having an imperforate tip at oneend shaped for blunt dissection of tissue, a central passage extendingthrough said catheter from the opposite end thereof to said tip, saidpassage terminating adjacent said tip in a transverse end wall; anelongated cannula disposed in said catheter in sliding, telescopedrelation therewith and having a traverse end surface engaging said endwall, the other end portion of said cannula projecting through saidopposite end of the catheter; means on said other cannula end forming agrip for said placement device whereby said imperforate tip is pressedthrough tissue by a force applied through the cannula against saidtransverse end wall; and two laterally opening ports formed on oppositesides of said catheter adjacent said tip at the opposite ends of across-passage through the catheter between said end wall and said tip,said cross-passage being connected to said catheter passage by aconnecting port centrally located in said end wall to communicate withthe interior of said cannula through said end surface thereof.
 4. Acatheter placement device as defined in claim 3 in which said tip isgenerally hemispherical in shape and said cross-passage is offset fromthe center of curvature toward said tip, said tip being thickenedlongitudinally of said cross-passage to a nearly rectangular shape todispose said laterally opening ports in planes extending substantiallylongitudinally of said catheter.